Dating in the dark after the show
So suggests new research that tracked changes in two genes thought to help regulate brain growth, changes that appeared well after the rise of modern humans 200,000 years ago.
That the defining feature of humans — our large brains — continued to evolve as recently as 5,800 years ago, and may be doing so today, promises to surprise the average person, if not biologists.
Some linguists believe that Kurgan horsemen carried them out of central Asia 6,000 years ago.
Aside from not knowing what the gene variants actually do, no one knows how precise the model Lahn used to date them is, Collins added.
Lahn's own calculations acknowledge that the microcephalin variant could have arisen anywhere from 14,000 to 60,000 years ago, and that the uncertainty about the ASPM variant ranged from 500 to 14,000 years ago.
In fact, the variations were so common they couldn't be accidental mutations but instead were probably due to natural selection, where genetic changes that are favorable to a species quickly gain a foothold and begin to spread, the researchers report.
Lahn offers an analogy: Medieval monks would copy manuscripts and each copy would inevitably contain errors — accidental mutations.